Power and free conveyor system with positively controlled dog

ABSTRACT

A power and free conveyor includes a trolley with a driving dog pivotable about a vertical axis. The dog can be set by a trackside abutment to either one of operative and inoperative positions. The dog is normally held in a selected position by an element which is fast with the dog and lies in a longitudinally extending slot defined by the track. The slot has wider portions within which the holding element is free to turn and narrower portions within which the holding element cannot turn.

United States Patent [1 1 [4 Oct. 7, 1975 1 POWER AND FREE CONVEYOR SYSTEM WITH POSITIVELY CONTROLLED DOG [75] Inventor: Walter Desmond 0rd, Birmingham,

England [73] Assignee: Redman Fisher Engineering Limited, Tipton, England 22 Filed: Dec. 28, 1973 211 Appl. No.: 429,638

[30] Foreign Application Priority Data June 22, 1973 United Kingdom 29/69/73 [52] US. Cl 104/172 S; 104/89 [51] Int. Cl. B61B 13/00 [58] Field of Search 104/172 S, 172 R, 172 BT, 104/172 C, 165, 89, 96

[56] References Cited UNITED STATES PATENTS 3,420,188 1/1969 Dehne et a1. 104/172 S Ross 104/172 S X DeGoodl et al. 104/172 S Primary Examiner-Lloyd L. King Assistant ExarninerRandolph A. Reese Attorney, A em, or FirmSpencer & Kaye [5 7 ABSTRACT A power and free conveyor includes a trolley with a driving dog pivotable about a vertical axis. The dog can be set by a track-side abutment to either one of operativeand inoperative positions. The dog is normally held in a selected position by an element which is fast with the dog and lies in a longitudinally extending slot defined by the track. The slot has wider portions within which the holding element is free to turn and narrower portions within which the holding element cannot turn.

9 Claims, 6 Drawing Figures Sheet 1 of6 3,910,199

l/ Iillllll\ Oct. 7,1975

.8. Pawn? US. Patent Oct. 7,1975 Sheet 2 of6 3,910,199

US. Patent (M11975 Sheet 3 of6 3,910,199

US. Patent 0a. 7,1975 Sheet4 of6 3,910,199

U.S. Patent 0a. 7,1975 Sheet 5 of6 3,910,199

lllllv MOE Oct. 7,1975 Sheet 6 of 6 US. Patent POWER AND FREE CONVEYOR SYSTEM WITH POSITIVELY CONTROLLED DOG BACKGROUND OF THE INVENTION The invention relates to a conveyor system of-the It is an object of the present invention to provide a kind comprising a track for supporting for advancement therealong a plurality of trolleys and an elongate power-driven propelling element supported for movement along a path parallel to said track, the propelling element and at least some of the trolleys having dogs which can co-operate to transmit drive from the propelling element to the trolleys.

It is common for the trolleys to be coupled together into one or more trains and in such cases each train is normally driven by engagement between a single driving dog of the train and a co-operating dog of the propelling element. It is normal to provide in each train one or more auxiliary dogs additional to the driving dog through which the train is normally driven. Examples of such auxiliary dogs are a hold-back dog which is engageable with dogs of the propelling element to prevent the train overrunning the propelling element, and an auxiliary driving dog by meansof which the train can be driven under circumstances such that the main driving dog is temporarily inoperative.

One circumstance under which the main driving dog may be inoperative is when a train is passing-from the control of one propelling element to the control of a further propelling element. The arrangement is normally such that the main driving dog is dis-engaged from the co-operating dog of the first propelling element before it is engaged by a dog of the second propelling element. It is therefore common to provide an auxiliary driving dog by means of which the train can be driven from the first propelling element during the period for which the main driving dog is not engaged by a dog of either propelling element.

To avoid risk of interference of onepropelling element with operation of the other propelling element, it is desirable that an auxiliary driving dog should normally be inoperative and should be brought into opera tion only for the period during which the main driving dog is inoperative. It has therefore been proposed that an auxiliary dog should be mounted on a trolley for movement between operative and inoperative positions and there should beprovided at a predetermined position along the track means for moving the auxiliary dog to its operative position. An example of such an arrangement is described in US. Patent Specification No. 3,541,352. In this specification there is described an auxiliary dog which is mounted on a trolley for pivoting movement about a horizontal axis and is provided with a cam follower for engagement with a ramp fixed to the track. When the follower engages with the ramp during advancement of the trolley, the auxiliary dog is pivoted upwardly to an operative position. When the follower passes off the ramp, the dog falls back to an inoperative position.

One disadvantage of the arrangement described in US. Pat. No. 3,541,352 is that gravitational forces are relied upon to return the auxiliary dog to its inoperative position. It is therefore possible that, if free pivoting of the auxiliary dog is inhibited by, for example, the penetration of foreign matter between the relatively movable bearing surfaces of the pivot, or lack of proper maintenance and lubrication, the auxiliary dog may fail to return to its inoperative position. This may lead to jamming of the conveyor system and possibly to damage thereof.

SUMMARY OF Tll-IE INVENTION conveyor system of the kind referred to whereof a trolley has a dog which, when the system is in use, is displaced positively in both directions between operative and inoperative positions with respect to the dogs of the propelling element.

According to the present invention there is provided a conveyor system of the kind referred to wherein there is provided on at least one of the trolleys a dog which is settable in a selected one of an operative position and an inoperative position with respect to the driving dogs of the power'driven element, there is provided at a first position along the track a first control means for setting the settable dog of said one trolley positively in its operative position when said one trolley passes said first position, and there is provided at a second position along the track second control means for setting the settable dog positively in its inoperative position when said one trolley passes said second position.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows in side elevation one trolley of a power and free conveyor. system, together with one portion of a track on which thetrolley runs,

A FIG. 2 shows the trolley and track in section on the line II II of FIG. 1,

FIG. 3 shows a plan view of the trolley and a portion of the track on which it runs,

FIG. 4 shows in plan view and on an enlarged scale certain parts of a modified version of the trolley of FIG.

FIG. 5 is a view in side elevation and on a scale intermediate those of FIGS. 1 and 4, showing the parts of the modifiedtrolley shown in FIG. 4, together with a part of the track on which the trolley runs and control means mounted on the track, and

FIG. 6 is an end view of the parts shown in FIG. 5 on the same scale as FIG. 5.

DESCRIPTION OF SELECTED EMBODIMENTS The conveyor system illustrated in FIGS. 1, 2 and 3 comprises a load bearing track comprising two channel section members 10 and 11 which are arranged with their respective webs 12 vertical and with their flanges 13 directed towards one another. A power driven propelling element (not shown) in the form of an endless chain is supported for movement along a path above and parallel to the track 10, 11. A plurality of driving dogs are attached to the chain and project downwardly therefrom towards the gap between the track portions 10 and 11. One such driving dog is indicated at 14 in FIGS. 1 and 2. These driving dogs would normally be spaced at regular intervals along the power driven chain.

The conveyor system further comprises a plurality of trolleys, one only of which is illustrated. The particular trolley shown is intended for use as the trailing trolley of a train of coupled trolleys. The trolley shown has a body 15 comprising two vertical plates 16 arranged in side-by-side spaced relation. Two pairs of running wheels 17 which run on the lower flanges of the track portions 10 and 11 are mounted on the body 15. There are also mounted on the body guide wheels 18 which are rotatable about respective vertical axes and run between the opposed flanges of the track portions and 11. An opening 19 is formed in the body to enable a load to be suspended therefrom.

The trolley further includes an auxiliary driving dog 20 which projects upwardly from the body towards the power driven propelling element and which can be engaged by the driving dogs 14. The auxiliary driving dog is intended to be operative only at times when a main driving dog, normally provided on the leading trolley of a train, is inoperative. Accordingly, the dog 20 is'mounted on the trolley for movement between an operative position in which it lies in the path of the driving dogs 14 and an inoperative position in which it is off-set from the path of the dogs 14. In FIGS. 1 and 3, the auxiliary driving dog is shown in its operative position and in FIG. 2 the auxiliary driving dog is shown in full lines in its operative position and in broken lines at- 20a in its inoperative position.

The auxiliary driving dog 20 is arranged for pivotal movement between its operative and inoperative positions about a vertical axis 21. The dog 20 is rigidly secured to and projects upwardly from a carrier element 22 comprising an upper wall 23 which is of square shape, as viewed in plan, and is formed with a central bearing opening. A pivot 24 is received within the bearing opening of the carrier element 22, this pivot projecting upwardly from a horizontal plate 25 to which it is secured. The plate 25 is secured to a vertical plate 26 which is received in and bolted to the body 15 of the trolley. An annular washer 27a is interposed between the horizontal plate 25 and the wall 23 and the carrier element is retained on the pivot 24 by means of a circlip 27.

The carrier element 22 further includes lateral walls 28 which project downwardly from the upper wall 23 through the slot defined by the free edges of the upper flanges l3of the track. The dimensions of the carrier element 22 are such that, as shown in FIG. 3, a small clearance is normally provided between the lateral walls 28 and the flanges of the track. Owing to the square shape of the carrier element, this small clearance is, not sufficient to permit pivoting movement of the carrier element about the axis 21 and the auxiliary driving dog 20 is therefore normally held in one or other of its operative and inoperative positions.

At certain positions along the track, the upper flanges 13 are cut away as shown at 29 and 30 in FIG. 3 to provide sufficient clearance between the flanges and the carrier element 22 to permit pivoting of the dog ular to the direction of travel for face-to-face engagement with the abutment 31. When the arm 32 is engaged with the abutment 31 and the trolley continues to move past the abutment, the carrier element 22 turns about the axis 21, in an anti-clockwise direction as viewed in FIG. 3, through an angle of 90. The face 34 of the arm 32 is then parallel to the direction of travel and the arm just clears the abutment 31 so that the abutment does not prevent passage of the trolley. The free end face 35 of the arm 33 is perpendicular to the end face 34 and when the latter is parallel to the direction of travel, face 35 is perpendicular thereto and facing forwardly. Thus, when the dog 20 is in its inoperative position and the trolley moves past an abutment on the side of the track opposite to the abutment 31, the arm 33 will be engaged and will cause the carrier element 22 to pivot through an angle of 90 in the clockwise direction, as viewed in FIG. 3, thereby returning the auxiliary dog 20 to its operative position.

It will be noted that the auxiliary dog 20 is moved in both directions between its operative and inoperative positions positively. Reliance is not placed on gravitational or other forces which merely bias the auxiliary dog towards one or other of its positions. Furthermore, when the auxiliary dog has been set by the control means either to its operative position or to its inoperative position, it does not tend to move out of such position until it is moved once more by the control means. A stop 36 projects from the lower extremity of one of the lateral walls 28 for engagement with the body 15 of the trolley to limit pivoting movement of the carrier element 22 about the axis 21 to a range of approximately 90. Whilst the particular example of trolley shown in FIGS. 1 to 3 is arranged for pivoting of the auxiliary dog in opposite directions between its operative and inoperative positions, it will be appreciated that the trolley could alternatively be arranged for unithe carrier element 22 a striker arm 32. This striker arm projects radially of the axis 21. A furtherstriker arm 33 projects from the carrier element 22 in a direction diametrically opposite to that of the arm 32, the arm 33 being provided for co-operation with abutments similar to the abutment 31 but provided on the other side of the track.

As shown in FIG. 3, when the dog 20 occupies its operative position, the striker arms 32, 33 project in directions inclined to the direction of travel at 45. The free end face 34 of the arm 32 then extends perpendicv a support 138 for movement relative thereto about a directional movement of the auxiliary dog, in which case the dog wouldbe adapted to co-operate with the driving dogs 14 both when it is in a position before the axis 21 and when in a position behind the axis 21.

In FIGS. 4, 5 and 6 there is illustrated a modified version of the trolley shown in FIGS. 1, 2 and 3, which ously described with reference to FIGS. 1, 2 and 3 areindicated by like reference numerals with the prefix 1 and the preceding description .is deemed to apply thereto, except for the differences hereinafter mentioned. i

The carrier element 122 of the trolley shown in FIGS.

7 5, 6 and 7 is in the formof a circular plate which is disposedhorizontally and is mounted on a vertical pivot 124. Striker arms 132 and 133 are welded onto the plate 122 at the upper side thereof and project in diametrically opposite directions for co-operation 'with abutments 131 rigidly secured to the track. The auxiliary dog is also rigidly secured to the plate 122 at the upper side thereof and projects upwardly from the plate.

For holding the carrier plate 122 in a position to which it is set, there is provided holding means in the form of a latch 137. The latch-is pivotally mounted on 120 about the axis 121. A further endjportion 143 of the latch is considerably more. massive than the end portion 142 and, since these end portions are spaced approximately equally on opposite sides of the latch pivot, the end portion 143 biases the end portion 142 upwardly into its holding position.

For moving the latch 137 to its releasing position, the control means further comprises a cam 144 which is fixed relative to the track portion 1 l 1 and is positioned for engagement with the end portion 143 of the latch. The cam presents towards an approaching latch an upwardly inclined surface up which the end portion 143 is drawn as a trolley moves past the cam. Accordingly, the cam causes the end portion 142 to move downwardly out of the notch in which it is engaged to a releasing position in which it is clear of the plate 122. The cam 144 is arranged to hold the latch in its releasing position whilst an adjacent abutment 131 is engaged by one of the striker arms 132, 133. The latch moves out of engagement with the cam when the notch has moved 6 table asel'ected' 'one of an operative position and an inoperative positionwith respect td the driving dogs of the power driven element and in a gen erally horizontal plane, there is provided at a first position along the track first control meansfor acting on the settable dog of said n trolleyw hensaid ofne trolley' passes said first position such a mariner as to set the dog positively in its operative position, and there is provided at a second position alongthe track second control means for acting on the settable dog when said one trolley passes said secondposition insuch a rnanner as to set the dog positively in its inoperative position.

2. In a conveyor system comprising a track, a plurality of trolleys which run on the track, a power driven element supported for movement along a path parallel to the track, a plurality of driving dogs on the power driven element and dogs on at least some of the trolleys for co-operation with the driving dogs on the power driven element, the improvement wherein:

out of register with the end portion 142. This end portion is then urged into engagement with the underside of the plate 122 until the other notch is brought into register, whereupon the end portion enters the notch to hold the plate 122 once more against pivoting movement.

A cam 144 for cooperation with the latch 137 is provided at one side of the track on the track portion 1 1 1 near to each abutment 131, irrespective of whether the abutment is provided at the same side of the track as the cam, or at the opposite side of the track. Where an abutment and a cam are mounted at the same side of the track, they may be mounted on a common bracket 145, as shown in FIGS. 5 and 6. Where the abutment and cam are on opposite sides of the track, they would be provided with individual brackets.

Upward movement of the end portion 142 of the latch within each of the notches 140, 141 is limited by a cap 146 which extends over the notch at the upper side of the plate 122.

The trolleys illustrated in FIGS. 1 through 3 and 4 through 6 may be further modified by arranging the auxiliary dog for pivoting movement about an axis which is inclined to the vertical and lies in a vertical plane which extends in the direction of travel. With such a modification, pivoting of the dog would cause it to move upwardly and downwardly, as well as laterally, so that in its inoperative position it may lie below the path of travel of the driving dogs 14, rather than beside such path. i

I claim:

1. In a conveyor system comprising a track, a plurality of trolleys which run on the track, a power driven element supported for movement along a path parallel to the track, a plurality of driving dogs on the power driven element and dogs on at least some of the trolleys for co-operation with the driving dogs on the power driven element, the improvement wherein: there is provided on at least one of said trolleys a dog which is setthere is provided on at least one of said trolleys a dog which is settable in a selected one of an operative position and an inoperative position with respect to the driving dogs of the power driven element, said settable dog is mounted on said one trolley for movement about a pivot axis which is substantially vertical when the trolley is on a horizontal length of track,

there is provided at a first position along the track first control means for setting the settable dog of said one trolley positively in its operative position when said one trolley passes said first position, and there is provided at a second position along the track second control means for setting the settable dog positively in its inoperative position when said one trolley passes said second position.

3. The improvement according to claim 2 wherein said settable dog is rigidly connected to at least one arm which projects radially of said pivot axis for engagement with the control means.

4. The improvement according to claim 3 wherein the control means comprises a plurality of abutments spaced from one another along the track.

5. The improvement according to claim 3 wherein the settable dog is rigidly connected to two arms which project in diametrically opposite directions with respect to the pivot axis for engagement with the control means.

6. The improvement according to claim 2 wherein stop means is provided for limiting pivotal movement of the settable dog to a range of approximately 90.

7. The improvement according to claim 2 wherein:

holding means is provided for preventing pivotal movement of the settable dog during periods when the dog is required to remain in one of its operative and inoperative positions,

the holding means comprises an element rigidly secured to the settable dog, the track defines a longitudinally extending slot,

said element normally lies within said slot, there is clearance between said element and the boundaries of said slot,

along parts of the track, said clearance is insufficient to permit pivoting of said element with the settable dog about said axis, and

along further parts of the track, said clearance is sufficient to permit pivoting of said element with the settable dog about said axis.

the control means is arranged for displacing the latch to its releasing position preparatory to displacing the dog between its operative and inoperative positions.

9. The improvement according to claim 8 wherein said latch ispivotally mounted on the trolley and the control means comprises a cam which engages with the latch as the trolley passes the cam to pivot the latch to its releasing position. 

1. In a conveyor system comprising a track, a plurality of trolleys which run on the track, a power driven element supported for movement along a path parallel to the track, a plurality of driving dogs on the power driven element and dogs on at least some of the trolleys for co-operation with the driving dogs on the power driven element, the improvement wherein: there is provided on at least one of said trolleys a dog which is settable in a selected one of an operative position and an inoperative position with respect to the driving dogs of the power driven element and in a generally horizontal plane, there is provided at a first position along the track first control means for acting on the settable dog of said one trolley when said one trolley passes said first position in such a manner as to set the dog positively in its operative position, and there is provided at a second position along the track second control means for acting on the settable dog when said one trolley passes said second position in such a manner as to set the dog positively in its inoperative position.
 2. In a conveyor system comprising a track, a plurality of trolleys which run on the track, a power driven element supported for movement along a path parallel to the track, a plurality of driving dogs on the power driven element and dogs on at least some of the trolleys for co-operation with the driving dogs on the power driven element, the improvement wherein: there is provided on at least one of said trolleys a dog which is settable in a selected one of an operative position and an inoperative position with respect to the driving dogs of the power driven element, said settable dog is mounted on said one trolley for movement about a pivot axis which is substantially vertical when the trolley is on a horizontal length of track, there is provided at a first position along the track first control means for setting the settable dog of said one trolley positively in its operative position when said one trolley passes said first position, and there is provided at a second position along the track second control means for setting the settable dog positively in its inoperative position when said one trolley passes said second position.
 3. The improvement according to claim 2 wherein said settaBle dog is rigidly connected to at least one arm which projects radially of said pivot axis for engagement with the control means.
 4. The improvement according to claim 3 wherein the control means comprises a plurality of abutments spaced from one another along the track.
 5. The improvement according to claim 3 wherein the settable dog is rigidly connected to two arms which project in diametrically opposite directions with respect to the pivot axis for engagement with the control means.
 6. The improvement according to claim 2 wherein stop means is provided for limiting pivotal movement of the settable dog to a range of approximately 90*.
 7. The improvement according to claim 2 wherein: holding means is provided for preventing pivotal movement of the settable dog during periods when the dog is required to remain in one of its operative and inoperative positions, the holding means comprises an element rigidly secured to the settable dog, the track defines a longitudinally extending slot, said element normally lies within said slot, there is clearance between said element and the boundaries of said slot, along parts of the track, said clearance is insufficient to permit pivoting of said element with the settable dog about said axis, and along further parts of the track, said clearance is sufficient to permit pivoting of said element with the settable dog about said axis.
 8. The improvement according to claim 2 wherein: holding means is provided for preventing pivotal movement of the settable dog during periods when the dog is required to remain in one of its operative and inoperative positions, the holding means comprises a latch, said latch is mounted on the trolley for movement between holding and releasing positions in the former of which it holds the dog in one of the operative and inoperative positions and in the latter of which positions of the latch the dog is free to pivot, and the control means is arranged for displacing the latch to its releasing position preparatory to displacing the dog between its operative and inoperative positions.
 9. The improvement according to claim 8 wherein said latch is pivotally mounted on the trolley and the control means comprises a cam which engages with the latch as the trolley passes the cam to pivot the latch to its releasing position. 